Vapour growth of bulk anisotropic crystals: case study of α-HgI2

Thin films and single crystals of mercuric iodide (α-HgI2) have been investigated by scanning force microscopy. During the scan process, material evaporation is observed proceeding by hole formation and etching at steps. The ratio of etched volume per second and per interaction area between tip and mercuric iodide step edges is found to be constant for hole formation on an HgI2 crystal and for etching at a screw dislocation on HgI2 films. An estimate for the loading of the SFM tip gives a value comparable to the critical resolved shear stress in this material.

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“…[7][8][9] As source material highly purified mercuric iodide is used. [7][8][9] As source material highly purified mercuric iodide is used.…”

Section: Methodsmentioning

confidence: 99%

Layer-by-layer etching of HgI2 films and crystals by scanning force microscopy

Lang

Erler

Roßberg

et al. 1996

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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“…These cycles, usually not strictly constrained or programmed as in the original or modified procedure, are employed only to nucleate a single crystallite and to avoid parasitic growth of other crystallites at this nucleation stage. The subsequent crystal growth then proceeds by increasing the apparent undercooling, which is T S − T CF , by either keeping T S constant while decreasing T CF [40], or keeping T CF constant while increasing T S .…”

Section: Vapor Growth Of Hgi 2 In the Vertical Furnacementioning

confidence: 99%

“…Because of parasitic growth of crystallites likely occur during nucleation, a tight temperature control is especially needed in this growth stage. As the growth progresses, morphological stability may become an issue and an overgrowth (a defect) on the crystal surface can happen [40]. Although growth striations caused by temperature swings in the temperature gradient reversal method have been avoided, nevertheless, striations caused by thermal instability are still encountered [24].…”

Section: Vapor Growth Of Hgi 2 In the Vertical Furnacementioning

confidence: 99%

Vapor Growth of Mercuric Iodide Tetragonal Prismatic Crystals

Ariesanti¹

2013

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Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information pound-force/inch 2 (psi) pound-mass (lbm avoirdupois) pound-mass-foot 2 (moment of inertia) pound-mass/foot 3 rad (radiation dose absorbed) roentgen shake slug torr (mm Hg, 0 0 C) *The bacquerel (Bq) is the SI unit of radioactivity; 1 Bq = 1 event/s. **The Gray (GY) is the SI unit of absorbed radiation.1.000 000 x E -10 1.013 25 x E +2 1.000 000 x E +2 1.000 000 x E -28 1.054 350 x E +3 4.184 000 4.184 000 x E -2 3.700 000 x E +1 1.745 329 x E -2 t k = (t o f + 459.67)/1.8 1.602 19 x E -19 1.000 000 x E -7 1.000 000 x E -7 3.048 000 x E -1 1.355 818 3.785 412 x E -3 2.540 000 x E -2 1.000 000 x E +9 1.000 000 4.183 4.448 222 x E +3 6.894 757 x E +3 1.000 000 x E +2 1.000 000 x E -6 2.540 000 x E -5 1.609 344 x E +3 2.834 952 x E -2 4.448 222 1.129 848 x E -1 1.751 268 x E +2 4.788 026 x E -2 6.894 757 4.535 924 x E -1 4.214 011 x E -2 1.601 846 x E +1 1.000 000 x E -2 2.579 760 x E -4 1.000 000 x E -8 1.459 390 x E +1 1.

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“…However, these vapor pressures indicate for the three compounds crystal growth from the vapor as a possible method for growing crystals of usable size at practical growth rates. In the case of mercuric iodide growth from the vapor has been the main method employed due to the problems of the growth from the melt because of the phase transformation previously mentioned [14][15]. Lead iodide crystals, instead, have been traditionally grown from the melt by methods like traveling molten zone (TMZ) [6,7,16], Bridgman and Czochralski [6,[18][19].…”

Section: Introductionmentioning

confidence: 99%

Growth of bismuth tri‐iodide platelets by the physical vapor deposition method

Cuña

Noguera

Saucedo

et al. 2004

Cryst. Res. Technol.

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The work reports the growth of single BI 3 crystals with platelets habit. Platelets were grown by physical vapor deposition (PVD) in a high vacuum atmosphere and with argon, polymer or iodine as additives. Crystals grew in the zone of maximum temperature gradient, perpendicular to the ampoule wall. Crystals grown with argon as additive show a very shining surface, have hexagonal (0 0 l) faces, sizes up to 20 x 10 mm 2 and thicknesses up to 100 µm. They were characterized by optical microscopy and scanning electron microscopy (SEM). Dendritic-like structures were found to be their main surface defect. SEM indicates that they grow from the staking of hexagonal unities. Electrical properties of the crystals grown under different growth conditions were determined. Resistivities up to 2 x 10 12 Ωcm (the best reported value for monocrystals of this material) were obtained. X-ray response was measured by irradiation of the platelets with a 241 Am source of 3.5 mR/h. A comparison of results according to the growth conditions was made. Properties of the crystals grown by this method are compared with the ones measured for others previously grown from the melt. Also, results for bismuth tri-iodide platelets are compared with the ones obtained for mercuric and lead iodide platelets.

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Vapour growth of bulk anisotropic crystals: case study of α-HgI2

Cited by 34 publications

References 11 publications

Layer-by-layer etching of HgI2 films and crystals by scanning force microscopy

Layer-by-layer etching of HgI2 films and crystals by scanning force microscopy

Vapor Growth of Mercuric Iodide Tetragonal Prismatic Crystals

Growth of bismuth tri‐iodide platelets by the physical vapor deposition method

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